A cousin of slain Yuendumu teenager Kumanjayi Walker has called for an investigation into "horrific" text conversations held by the NT cop who shot and killed him.

The coronial inquest into Mr Walker's 2019 shooting death at the hands of NT Constable Zachary Rolfe, who was earlier this year found not guilty of murder, on Wednesday heard a host of confronting conversations police and lawyers had attempted to argue were not relevant.

Text conversations between Mr Rolfe and colleagues included derogatory terms for Indigenous people such as "c***s", "n****s", neanderthals and "grubby f***s".

NT Police Force counsel Ian Freckelton said the messages were repugnant but did not represent the values of territory police.

"It is important that a misimpression not be propagated that this modest number of offensive utterances by text messages be imputed to the whole police force," he said.

"To do so would run the risk of diminishing the respect in which the force is generally held."

Warlpiri woman Samara Fernandez-Brown, Walker's cousin, said it was woeful to see police officers, including high ranking members, hold such attitudes towards Indigenous people.

"It is absolutely horrific, though not surprising, to hear some of the text messages that were downloaded from Zachary Rolfe's phone," she said.

"These text messages very clearly outline his attitudes, and the attitudes of some of his peers towards Aboriginal people.

"Though amongst the text messages included there are only a few officers engaging in the harmful, racist, sexist, homophobic and highly offensive conversations, I believe there must be investigations and disciplinary actions."

Ms Fernandez-Brown said passing the messages off as "a few rotten eggs" would deny the chance to create meaningful change.

The three-month inquest continues today.

• With AAP